Vu An T, Phillips Jeffrey S, Kay Kendrick, Phillips Matthew E, Johnson Matthew R, Shinkareva Svetlana V, Tubridy Shannon, Millin Rachel, Grossman Murray, Gureckis Todd, Bhattacharyya Rajan, Yacoub Essa
a Center for Magnetic Resonance Research , University of Minnesota , Minneapolis , MN , USA.
b Department of Neurology , University of Pennsylvania , Philadelphia , PA , USA.
Cogn Neuropsychol. 2016 May-Jun;33(3-4):265-75. doi: 10.1080/02643294.2016.1195343.
The blood-oxygen-level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments is generally regarded as sluggish and poorly suited for probing neural function at the rapid timescales involved in sentence comprehension. However, recent studies have shown the value of acquiring data with very short repetition times (TRs), not merely in terms of improvements in contrast to noise ratio (CNR) through averaging, but also in terms of additional fine-grained temporal information. Using multiband-accelerated fMRI, we achieved whole-brain scans at 3-mm resolution with a TR of just 500 ms at both 3T and 7T field strengths. By taking advantage of word timing information, we found that word decoding accuracy across two separate sets of scan sessions improved significantly, with better overall performance at 7T than at 3T. The effect of TR was also investigated; we found that substantial word timing information can be extracted using fast TRs, with diminishing benefits beyond TRs of 1000 ms.
在功能磁共振成像（fMRI）实验中测量的血氧水平依赖（BOLD）信号通常被认为较为迟缓，不太适合在句子理解所涉及的快速时间尺度上探测神经功能。然而，最近的研究表明了以非常短的重复时间（TR）获取数据的价值，这不仅体现在通过平均提高对比度噪声比（CNR）方面，还体现在额外的细粒度时间信息方面。使用多频段加速fMRI，我们在3T和7T场强下均实现了以仅500毫秒的TR进行3毫米分辨率的全脑扫描。通过利用单词时间信息，我们发现跨两个独立扫描会话集的单词解码准确率显著提高，7T时的整体性能优于3T。我们还研究了TR的影响；我们发现使用快速TR可以提取大量单词时间信息，超过1000毫秒的TR其益处逐渐减少。
